I spiral cut my old socks (most were former hiking socks beyond mending) into long strips and crocheted them into a sturdy rug for the back entrance. I actually made the rug a few years ago when my "waste not, want not" upbringing challenged me to do something with my holey socks and I needed a rug.

The danger is using the old socks is that (at least for me) once people find out you use an item, they'll want to give you theirs. So, I had many offers of old, but clean socks after making the rug. (Side note: the socks also function well as dust rags)